The postpartum period is accompanied by dramatic endocrine and behavioral alterations. Among these changes are increased basal glucocorticoid levels and decreased estrogen levels. Elevated glucocorticoid and diminished estrogen levels have been associated with cognitive impairment and enhanced anxiety in adult virgin male and female rodents and yet, the majority of postpartum females do not exhibit these negative outcomes. Since motherhood is also associated with elevations in oxytocin (OT), a neuropeptide that has been shown to buffer stress hormone effects on the brain and body, it's possible that OT protects against the potentially damaging postpartum hormonal milieu. The medial prefrontal cortex (mPFC) is a brain region that has been linked to mood disorders, cognitive behavior and maternal care. The mPFC is also sensitive to hormones - both estrogen and glucocorticoids alter dendritic architecture and dendritic spines, sites of excitatory synapses, in the mPFC. During the mentored phase of the award in the laboratory of Prof. Elizabeth Gould, I will investigate whether the structure of the postpartum mPFC is resistant to the detrimental postpartum hormonal environment and whether these changes underlie mPFC dependent behaviors. This work will set the stage for the independent phase of the award which will involve examining whether OT in the mPFC mediates structural and/or behavioral resilience during the postpartum period. The immediate goal of this research is to elucidate the effects of motherhood on mPFC structure and function with the broader objective of obtaining a faculty position where I can continue to identify the factors and mechanisms which underlie resilience of the maternal brain as an independent scientist. Relevance: For many women, becoming a mother is one of the most significant and rewarding human experiences. However, the dramatic hormonal changes that occur during the postpartum period may predispose some new mothers to react negatively to the demands of parenting. Indeed, it is estimated that 10-15% of new mothers experience postpartum depression and/or anxiety. Since the mPFC and OT have been linked to maternal care and mood disorders, understanding motherhood and OT induced structural alterations of the mPFC and their behavioral consequences may provide insight into the mechanisms underlying predisposition and resistance to mental illness.